82 NAIADES OF MISSOURI 



Pleurobema catillus (Conrad). 



("White Pigtoe,-" "Pink Pig-toe," "Solid Pig-toe.") 

 PL XX, Figs. 59 A and B. 



1836 — Unio catillus Conrad, Monog. Ill, p. 30, pi. XIII, fig. 2. 



1838 — Unio solidus Lea, Pr. Am. Phil. Soc, VI', pi. V, fig. 13. 



1845 — Unio fulgidus Lea, Pr. Am. Phil. Soc, p. 164; Tr. Am. Phil. 



Soc, X, 1848, p. 73, pi. IV, fig. 10. 

 1900b — Quadrida solida Simpson, Pr. U. S. Nat. Mus., XXII, p. 789. 



ANIMAL CHARACTERS. 



Nutritive Structures: — Branchial opening densely papil- 

 lose; anal finely papillose; supra-anal closely connected to anal; 

 gills rather long and wide, the inner being wider and longer, inner 

 laminae free from visceral mass; palpi long and connected about 

 two-thirds of their length antero-dorsad, soft parts tanned flesh- 

 color, yellowish in front of branchial opening, papillae blackish. 



Reproductive Structures: — Marsupia only occupying outer 

 gills, ovisacs swollen more centro-lengthwise tapering obtusely 

 at ventral edges; conglutinates leaf -like, compressed white; 

 glochidia semicircular, medium in size, hinge line nearly straight; 

 length and height equal (0.160 x xo.i6omm.). 



SHELL characters. 



External Structures: — Shell subtriangular with obtusely 

 pointed posterior end, very solid and thick through cardinal 

 hinge region, ventral line always more curved than dorsal; disk 

 smooth, post-umbonal ridge flattened; radial furrow in front 

 rather shallow and wide; beaks full, protruding but not beyond 

 anterior end; epidermis reddish brown with decided streaks of 

 green radiating ventrad from umbonal region. 



Internal Structures: — Cardinals heavy, double in both 

 valves; laterals double in right, single in left valve; interdentum 

 broad, short and thick; umbonal cavities shallow; nacre salmon 

 to rosy pink. » 



Sex Length Height Diameter Locality 



-f 82 X 65 X 41 (White R., Hollister) 



9 83 X 64 X 40 (Black R., Williamsville) 



d" 80 X 63 X 40 (White R., Hollister) 



Miscellaneous Remarks :^ — Conrad's catillus (described as 

 separate from coccineus by the author, but united by Simpson) is 



